The present invention relates to an image forming apparatus employing a liquid developer, in which a latent image formed on an image carrier is developed by a developing device using a liquid developer, the developed image is transferred from the image carrier to an intermediate transfer member at a primary transfer position of a primary transfer section, and the transferred developed image is transferred from the intermediate transfer member to a recording medium at a secondary transfer position of a secondary transfer section.
There have been proposed various wet-type image forming apparatuses capable of visualizing an electrostatic latent image by developing the latent image with a high concentration liquid developer containing a liquid solvent and a toner as solid substance dispersed therein. The developer employed in the wet-type image forming apparatus is formed by suspending solid substance (toner particles) in an electrical insulating organic solvent (carrier liquid) such as silicone oil, mineral oil, or cooking oil. The toner particles are very fine, for example, of about 1 μm in particle diameter. By employing such fine toner particles, the wet-type image forming apparatus can form high quality images as compared to a dry-type image forming apparatus employing powder-type toner particles of about 7 μm in particle diameter.
The carrier liquid composing the developer has not only a function of preventing the toner particles of about 1 μm in particle diameter from scattering, but also a function of making the toner particles charged and making the toner particles uniformly dispersed, and also a function of facilitating the transfer of toner particles by electric field during deployment and transfer process. Though the carrier liquid is a necessary ingredient for the toner conservation, the toner transport, the development, and the transfer process as mentioned above, the carrier liquid adheres also to non-imaging regions and the excess carrier liquid after development may cause deterioration of transfer. Accordingly, such a function is normally performed as to remove (squeeze) carrier liquid on the photoconductor and the intermediate transfer member (for example, JP-A-2002-296918). In addition, such a function is performed as to apply bias voltage on a roller such as a development roller so that the toner particles uniformly dispersed in the carrier liquid move and agglutinate to the surface of the roller (for example, JP-A-2000-56576). In the wet-type image forming apparatus comprising an intermediate transfer belt and further a secondary transfer belt, such a function is performed as to remove liquid developer (carrier liquid and solid substance) adhering to the belt surface by a cleaning blade (for example, JP-A-2002-189354).